Conventional solid ink printers, such as a microelectromechanical system jet (MEMSJet) printer, create an image on an image substrate by melting ink and delivering the melted ink to a printhead reservoir, where it is then transferred onto the substrate through a face plate in the printhead. When the solid ink printer is turned off or otherwise loses power, the ink that remains in the printhead reservoir can solidify and decrease in volume by about 15-20%. If the flexible, drop-ejecting membranes located in the printhead are in intimate contact with the ink as the ink solidifies, then the membranes can be deformed to the point of breaking as a result of the ink volume decrease. Further, when the ink in the printhead solidifies, additional ink from the ink supply system can be drawn into the printhead due to the volume reduction of the solidified ink. Upon thawing, the volume increase of the ink in the printhead can add pressure to the printhead, leading to added pressure to the membranes.
After the printer undergoes a solidify/thaw cycle, the performance of MEMSJet printheads can degrade due to broken membranes. Further, once broken, the membranes can no longer be used to eject ink drops, and ink can then get under the membranes and into the rest of the vent system, which can severely damage or destroy the printhead. The thawing process can also cause enough pressure buildup to delaminate the nozzle plate from the actuator walls, thereby damaging or destroying the printhead.
Known methods of preventing this damage include de-priming the printhead, or removing the ink from the printhead before it is allowed to solidify. Known de-priming processes can be performed during a normal printer shutdown or during a power fault. The known de-priming processes can cause the ink to be pulled from the printhead and back into an ink reservoir from which the ink is normally stored. However, this process can result various problems, such as, for example, contaminants being drawn into the nozzles, printhead, and ink reservoir. Thus, there is a need to overcome this and other problems of the prior art.